The invention of this application relates to a substrate processing apparatus used preferably for manufacturing display devices such as liquid crystal displays.
In manufacturing display devices such as liquid crystal displays and plasma displays, it is necessary to carry out a process onto a board-shaped material, which becomes the base of a device. This material is generally called xe2x80x9csubstratexe2x80x9d in this specification. In manufacturing liquid crystal displays, for example, a process to form a transparent electrode onto the front surface of a glass substrate is required.
Substrate processing apparatuses used for such a process comprise a chamber so that a substrate can be processed in a required environment. The chamber often comprises a pumping system to pump itself at a vacuum pressure or a gas-introduction system to introduce a required gas into itself. The substrate processing apparatuses often comprise a multiplicity of the chambers so that dissimilar processes can be carried out continually, or pressure can be reduced gradually from the atmosphere.
The conventional substrate processing apparatuses are classified into a couple of categories. One is called in-line type, and the other one is called cluster-tool type.
FIG. 6 schematically shows an in-line type apparatus as an example of conventional substrate processing apparatuses. The in-line type apparatus comprises a multiplicity of chambers 11, 2, 3, 12 provided in a line. A conveying system that conveys a substrate 9 through the chambers 11, 2, 3, 12 is provided. A gate valve 10 is provided at each boundary of the chambers 11, 2, 3, 12.
The substrate 9 is placed on a tray, which is conveyed to each chamber 11, 2, 3, 12 in this order by the conveying system. One of the chambers is a load-lock chamber 11 that is opened to the outside atmosphere when the substrate 9 is conveyed in. Another one of the chambers is an unload-lock chamber 12 that is opened to the outside atmosphere when the substrate 9 is conveyed out. One of rest chambers is a process chamber 2, i.e., chamber for process. Provided between the process chamber 2 and the load-lock chamber 11, and between the process chamber 2 and the unload-lock chamber 12 are the buffer chambers 3. The buffer chamber 3 is provided considering large pressure difference of the load-lock chamber 11 and the unload-lock chamber 12 from the process chamber 2. The buffer chambers 3 moderate the difference by maintaining the intermediate pressure of the difference.
As shown in FIG. 6, the conveying system conveys the tray 91 on which the substrate 9 is placed, by conveying rollers 41. The conveying rollers 41 are provided at both ends of a rotary rod, which are provided horizontally and perpendicularly to the conveying direction. The conveying system is composed of a multi-combination of the rotary rods and the couples of the conveying rollers 41, which are arrayed along the conveying direction. As shown in FIG. 6, the substrate 9 is conveyed and processed posing horizontally.
On the other hand, FIG. 7 schematically shows a cluster-tool type apparatus as another example of conventional substrate processing apparatuses. The cluster tool type apparatus has the layout where a load-lock chamber 11 and a plurality of process chambers 2 are provided around a transfer chamber 5 having a transfer robot 42. The example shown in FIG. 7 has two load-lock chambers 11. Gate valves 10 are provided between the transfer chamber 5 and each load-lock chamber 11, and between each transfer chamber 5 and the process chamber 2.
The transfer robot 42 takes a substrate 9 out of one load-lock chambers 11 and transfers it to each process chamber 2 in order. After the whole processes are finished, the transfer robot 42 returns the substrate 9 to the one or the other load-lock chambers 11. Though the chambers 11 in FIG. 7 have the function as an unload-lock chamber, the name xe2x80x9cload-lock chamberxe2x80x9d is still used.
The transfer robot 42 comprises a multi-jointed arm on top of which the substrate 9 is aboard. The transfer robot 42 transfers the substrate 9 by expansion-contraction, rotation and up-and-down motion of the arm. The substrate 9 keeps posing horizontally during transferring and during processes in process chambers 2.
Substrate-size enlargement is prominent tendency in the above-described substrate processing apparatuses. For example, not only as computer displays, but also liquid crystal displays and plasma displays are supposed to be made practical as on-the-wall television displays in the near future. Display area in the on-the-wall television displays is wider than that of the computer displays. Therefore, the substrates are enlarged as well. Besides, there is common tendency to produce a number of products from one substrate for improving productivity or reducing manufacturing cost. This is also bringing the enlargement of substrates.
With the substrate enlargement tendency at the background, the conventional substrate apparatuses bear, or will bear, following problems. First, in both of the in-line type and the cluster-tool type, a substrate keeps posing horizontally during conveying (or transferring) and processing. Therefore, when the substrate is enlarged, horizontal occupation area of each chamber is inevitably enlarged as well. As a result, the whole occupation area of the apparatus must be enlarged as well.
In the in-line type apparatus shown in FIG. 6, when each chamber 11, 2, 3, 12 is enlarged, the line length of the apparatus must be enlarged. In the manufacture of family-use on-the-wall television displays, it is supposedly required to process a substrate of about 1xc3x971.2 meter size. The in-line type apparatus that processes the substrate of this size would have the line-length of ten and several meters.
In the cluster-tool type apparatus shown in FIG. 7, the substrate enlargement directly brings the occupation area enlargement of each chamber, leading to increase of the whole occupation area of the apparatus. What is most serious in the cluster type is enlargement of the transfer chamber 5. As understood from FIG. 7, though the rotation axis of the transfer robot 42 is on the center of the transfer chamber 5, the substrate 9 is rotated apart from the center of the transfer chamber 5, because the substrate 9 is aboard on the top of the arm. Therefore, radius of the horizontal circular space necessary for the substrate rotation, hereinafter called xe2x80x9crequired space radiusxe2x80x9d, is more than twice of side length of the substrate. Therefore, when the substrate 9 is enlarged, the required space radius is doubled, enlarging the transfer chamber 5 more. For example, when the described substrate of 1xc3x971.2 meter size is processed, the required space radius easily exceeds 2 meters.
The transfer chamber 5 often needs to be pumped by a pumping system. When the transfer chamber 5 is enlarged, there arise problems that longer time is necessary for pumping at a required pressure, and higher cost is necessary for a high-performance pumping system 1. Besides, such the transfer chamber 5 is essentially unnecessary for the substrate process. This is not preferable design that such the unnecessary member occupies large space in the apparatus.
The second problem brought from the substrate enlargement at the background, is a bending of substrates. In display devices such as liquid crystal displays, to make a device thinner is great demand of the market as well as to make display area wider. From this demand, substrates do not tend to be thicker, rather tend to be thinner, nevertheless they are being enlarged. For example, thickness of the described substrate of 1xc3x971.2 meter size is just about 0.7 mm.
When such a thin substrate is conveyed (or transferred) and processed posing horizontally, the problem that the substrate bends from its weight arises. In the in-line type apparatus, for example, the substrate 9 easily bends downward at the portions not in contact with the conveying rollers 41. In the cluster-tool type apparatus as well, the substrate 9 bends at the sides not in contact with the arm.
When a process is carried out on a bending substrate, the process may lose homogeneity, which might bring a performance defect such as display unevenness. Besides, because non-uniform stress resides in the substrate 9, probability of substrate breaking may increase, decreasing product reliability.
For the cluster-tool type apparatus, practically it is becoming impossible to transfer the enlarged substrate 9 by the transfer robot 42. It is required to increase size and hardness of the arm sufficiently. In addition, it is required to carry out expansion-contraction, rotation and up-and-down motion of such the large-scale arm with high accuracy. However, it is very difficult to fabricate such the large-scale motion mechanism with sufficient accuracy. Therefore, transfer by the multi-joint arm robot is supposed to reach the practical limit in near future.
The third problem brought from the substrate enlargement at the background is the one concerning maintenance of apparatuses. Chambers composing an apparatus are capable of being opened for maintenance. For example, when a conveying (or transferring) error happens in a chamber, the inside of the chamber is checked after stopping operation of the apparatus. In case that the substrate is found not rightly on the conveying rollers or the arm, the substrate is restored to the right position, then resuming operation of the apparatus.
The chambers have a door for such maintenance. Usually, the upper board of the chambers is installed with a hinge so that it can be used as the door for checking the substrate. After opening the upper board, it is checked whether any foreign matter does not exist on the front surface of the substrate by eye observation.
However, when a chamber is enlarged from the substrate enlargement, the door is also enlarged. In case a substrate is enlarged to the described size, size of the door easily may exceed 1 xc3xcxcx9c1 meter. When the door is enlarged to such a size, it is no longer possible to open it by human force. A large-scale mechanism such as a crane would be required.
An object of this invention is to solve the problems described above. To accomplish this object, the invention presents a substrate processing apparatus comprising a substrate holder holding a substrate with a holding angle of 45 degrees to 90 degrees, a conveying system to convey the substrate by moving the substrate holder, a process chamber in which the substrate is processed, a load-lock chamber in which the substrate temporarily stays in conveying between the outside atmosphere and the process chamber, and an intermediate chamber provided between the process chamber and the load-lock chamber. The holding angle is the angle made of the substrate and the horizon. The conveying system conveys the substrate between the load-lock chamber and the intermediate chamber, and between the intermediate chamber and the process chamber. The conveying system conveys the substrate along the first direction, which is the direction from the load-lock chamber to the intermediate chamber or the direction from the intermediate chamber to the process chamber. Additionally, the conveying system conveys the substrate along the second direction that is perpendicular to the first direction.